The broad objective of this research proposal is to analyze and clarify the nature of the pulmonary vascular response to hemorrhagic shock and trauma. In this regard, the studies outlined will characterize the total as well as the regional pulmonary hemodynamic and functional adjustments following hemorrhagic shock and non-thoracic trauma under standardized controlled conditions in the intact dog. Additionally, the research proposal will attempt to determine and place into perspective the roles of the postulated factors: (1) pulmonary thromboembolization, (2) adrenergic mechanisms, (3) pulmonary hypoperfusion, and (4) blood gas and pH derangements in the pulmonary adjustments and in the etiology of pulmonary insufficiency following shock. The methodology to be employed includes physiological, histological and isotopic techniques. It is hoped that the proposed interdisciplinary studies pooling physiological, biomedical engineering, and surgical expertise will lead to a better understanding of the reasons for the pulmonary adjustments and of the pathophysiology of respiratory insufficiency following shock, thereby lending to a more meaningful approach to the clinical management of a patient in pulmonary insufficiency.